Expandable body cavity liner device

ABSTRACT

The present invention is an aneurysm treatment device for treating aneurysms of various shapes and sizes.

RELATED APPLICATION DATA

This application is a continuation of co-pending U.S. patent applicationSer. No. 10/107,689, filed Mar. 27, 2002, the priority of which isclaimed under 35 U.S.C. §120, and the contents of which is incorporatedherein by reference in its entirety, as though set forth in full.

BACKGROUND OF THE INVENTION

The present invention deals with a system for treating a vascularcavity. More specifically, the present invention is directed to vascularcavity liners and vascular cavity neck bridges.

While the present discussion proceeds with respect to aneurysms, it willbe appreciated that it can be applied to other vascular cavities (suchas vessels, lumens, etc.) as well. An aneurysm or vascular malformationis a localized stretching or distension of an artery due to a weakeningof the vessel wall. For example, “berry” aneurysms, i.e., smallspherical distensions, occur in the vessels of the brain. Thedistension—often referred to as the aneurysm sac—is related to defectsin the muscular coating of the artery and is probably degenerative inorigin. Rupture of aneurysms account for the majority of spontaneoushemorrhages. Approximately 25,000 intracranial aneurysms rupture everyyear in North America.

Several methods of treating aneurysms have been attempted, with varyingdegrees of success. At present, the treatment of aneurysms with drugs issubstantially ineffective. Also, extra-vascular surgery, referred to asopen craniotomy, for the purpose of preserving the parent artery isreplete with disadvantages. A patient subject to open craniotomy forintercranial aneurysms typically must undergo general anesthesia,surgical removal of part of the skull, brain retraction, dissectionaround the neck of the sac, and placement of a clip on the parent arteryto prevent bleeding or rebleeding.

Alternative treatments include endovascular occlusion where the interiorof the aneurysm is entered with a guidewire or a microcatheter. Anocclusion is formed within the sac with an intention to preserve theparent artery. One means for forming a mass is through the introductionof an embolic agent within the sac. Examples of embolic agents include adetachable coil, which is detached from the end of a guidewire, a liquidpolymer which polymerizes rapidly on contact with blood to form a firmmass, and embolic particles.

Endovascular occlusion is not without drawbacks. For example, there is arisk of overfilling the sac and consequent embolic agent migration intothe parent vessel. Overfilling of the sac also generates additionalpressure in the aneurysm.

Another means for forming a mass in the aneurysm sac involves theplacement of an elastic, expandable balloon or liner in the aneurysm.Detachable occlusion balloons have been used for a number of medicalprocedures. These balloons are carried at the end of a catheter and,once inflated can be detached from the catheter. Such a balloon may bepositioned within an aneurysm, filled and then detached from thecatheter. Deploying the balloon within the aneurysm can be ratherdifficult due to the high rates of blood flow through the aneurysm.Elastic balloons have exhibited problems with respect to performance andhave not been used endovascularly in some time.

This aneurysm filling technique also has its problems. As the balloon isfilled, the operator must be very careful not to overfill the balloondue to possible risk of rupturing the aneurysm. Accordingly, the balloonmay be too small, potentially resulting in the release of the balloonfrom the aneurysm into the blood stream. Furthermore, the balloon oftendoes not mold or shape to the odd-shaped contours of the aneurysmleaving room for blood to continue flowing through the aneurysm, orgenerating undesired pressure on the aneurysm wall.

Aneurysm liners are composed of a liner sac which is placed in theaneurysm and filled to occlude the aneurysm. A guidewire is inserted inthe liner. The guidewire carries the liner through the vasculature todeploy the liner in the aneurysm.

All of the present systems for treating aneurysms have disadvantages aswell. For example, while the aneurysm liner concept is intuitivelyattractive, it has posed a number of technical challenges. One primarychallenge involves the difficulty in producing a material that is robustenough to contain embolic material without inhibiting the ability of theembolics to conform to the aneurysm geometry itself, rather than thegeometry of the liner. For example, the elastic materials discussedabove generally require to much force to deform, and inelastic materialsthat deform readily do not have adequate memory to conform to theaneurysmal wall.

Different types of aneurysms also present different challenges. Forexample, aneurysms which have a particularly wide opening between theaneurysm sac and the parent vessel (“wide neck aneurysms”) presentdifficulties concerning the retention of embolic materials.Specifically, wide neck aneurysms make if very difficult to maintain theembolics, or occlusive materials, within the aneurysmal sac. This isespecially true of liquid embolic materials. Of course, should theembolic material enter the parent vessel, it poses an undesirable riskof occlusion in the parent vessel.

Some current aneurysm liner concepts are inadequate in treating largeraneurysms.

For example, some liner concepts involve forming the aneurysm liner of awoven or braided polymeric material such as polypropylene, polyester,nylon, urethane, teflon, etc. However, these mesh materials aredifficult to use in treating aneurysms larger than, for example, twelvemillimeters in diameter. Such mesh materials result in an assembly whichis too bulky when collapsed down onto the catheter for delivery. Inother words, the amount of materials required to fill a relatively largeaneurysm is very difficult to collapse down into a constrained, lowprofile, delivery configuration small enough to be delivered anddeployed without excess friction on the walls of the delivery catheteror other delivery lumen.

SUMMARY OF THE INVENTION

The present invention is a vascular cavity treatment device for treatingvascular cavities of various shapes and sizes and will be discussed byway of example as an aneurysm treatment device.

In one embodiment, the aneurysm treatment device includes an aneurysmliner formed of material having very low yield strength and very lowelasticity so that, with a relatively low amount of internal pressureexerted by, for example, embolic material, the aneurysm liner readilyplastically deforms to the internal geometry of the aneurysm sac. Asecond, reinforcing layer is deployed on the first material. Thereinforcing layer is more elastic than the first material and has a muchhigher yield strength. The reinforcing layer is illustratively disposedat the neck of the aneurysm liner device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate the deployment of an aneurysm liner in ananeurysm.

FIGS. 2A-2C illustrate an embodiment of an aneurysm liner being formedof materials with two different characteristics, one of them having avery low yield strength and the other having a high yield strength and agreater elasticity.

FIG. 2D illustrates the embodiment shown in FIGS. 2A-2C, withperforations therein.

FIGS. 3A-3C illustrate an embodiment of an aneurysm liner being formedof a balloon material having two different characteristics, portionsthereof being weaker than other portions thereof.

FIG. 3D illustrates the embodiment shown in FIGS. 3A-3C withperforations therein.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIGS. 1A-1C illustrate a portion of an aneurysm treatment device 10 in avessel 12 which has an aneurysm 14 therein, and thus illustrate thegeneral context of the present invention. Though the embodimentsdiscussed herein are discussed in conjunction with an aneurysm, it willbe appreciated that they can be used in substantially any vascularcavity or other bodily cavities. Aneurysm 14 is defined by aneurysmalsac 16 and neck 18. Device 10 includes, in the embodiment illustrated,delivery catheter 18, a pair of extender coils 21 and 22 and anexpandable liner 24 (aneurysm liner sac). Delivery catheter 20 has aproximal end that extends proximally to a position where it ismanipulable by an operator. The distal end of catheter 20 is releaseablyconnected to the liner 24 and coil 21. Coils 21 and 22 can either beattached to the liner or catheter, or unattached. In addition, there canalso be one or more coils disposed between coils 21 and 22 and axiallyaligned therewith.

When in the insertion position shown in FIG. 1A, coils 21 and 22 (andother optional coils therebetween) are axially aligned with one another,their length is sufficient to substantially hold liner 24 in a lowprofile position for insertion and manipulation within the vasculature.In one embodiment, coils 21 and 22 are axially aligned with one anotherand with catheter 20 through the use of a guidewire 26 which is disposedwithin the lumen of catheter 20, through coils 21 and 22 and liner 24,and out the distal end of catheter 22 and liner 24. Coils 21 and 22 areheld in an axially aligned conformation by guidewire 26 such that coils21 and 22 substantially conform to the curvature of guidewire 26. Coils21 and 22, rather than guidewire 26, can act to extend and even tensionliner 24.

FIG. 1B shows that treatment device 10 has been positioned throughvessel 12 and neck 18 into the sac 16 of aneurysm 14. Similar items aresimilarly numbered to those shown in FIG. 1A. In use, aneurysm treatmentdevice 10 can be preloaded or back loaded onto guidewire 26. Guidewire26 is manipulated through the vasculature from the entry site (such asthe femoral artery) to the region of vessel 12 containing the aneurysm.The distal tip of guidewire 26 is advanced across the neck 18 ofaneurysm 14 and into the aneurysm sac 16. This can be done using anydesirable visualization technique. In one embodiment, catheter 20 isplaced over guidewire 26 prior to positioning guidewire 26 in thevasculature, with several centimeters of guidewire 26 extending distalof the distal tip of catheter 20. Therefore, when the distal end ofguidewire 26 has passed the aneurysm neck 18, catheter 20 is positionedjust proximal of neck 18. Treatment device 10 is then advanced into theaneurysm sac 16.

In another embodiment, guidewire 26 is placed in the vasculature first.Once the distal end of guidewire 26 is moved past the aneurysm neck 18,into the aneurysm sac 16, catheter 20 is advanced over guidewire 26 suchthat the extender coils 21 and 22 are pushed distally along theguidewire by the catheter 20 until the aneurysm treatment device 10 isin place in the aneurysm sac 16.

FIG. 1C illustrates treatment device 10 deployed in aneurysm sac 16 inaccordance with one embodiment. Similar items are similarly numbered tothose shown in FIGS. 1A and 1B. Once device 10 is substantially fullywithin aneurysm sac 16, guidewire 26 is retracted proximally, but liner24 remains connected to delivery catheter 20. The distal end of deliverycatheter 20 holds expandable liner 24 in position within the aneurysmsac 16 while expandable liner 24 is filled with embolics. Expansion ofliner 24 occurs after the distal end of guidewire 26 is retracted fromthe coils 21 and 22.

As shown in FIG. 1C, once guidewire 26 has been retracted, coils 21 and22 recoil away from axial alignment with one another toward theperiphery of liner 24. In one illustrative embodiment, coils 21 and 22are biased to extend in opposite directions to enhance deployment of,and expansion of, liner 24 within aneurysm sac 16. If any coils aredisposed between coils 21 and 22 on guidewire 26, they simply fall awayand float within liner 24. Embolic material can now be introduced intoliner 24 through catheter 20 using substantially any desired method.Such methods include, for example, advancing coils or particles intoliner 24, pushing the embolic material into catheter 20 with guidewire26 completely removed, or infusing or injecting embolic material throughcatheter 20 into liner 24. Liner 24 is thus filled with a common embolicagent, such as detachable coils, particles, acrylics, hydrogel, etc.

Once liner 24 is filled, it is unable to be removed through aneurysmneck 18. Therefore, it is released from delivery catheter 20 anddelivery catheter 20 is removed from the treatment site. Detachment ofliner 24 from catheter 20 can be accomplished using any desired method,such as using electrolytic detachment, traction-based detachment, orother mechanical, electrical, heat-based, magnetic, chemical or otherdetachment.

FIGS. 1A-1C illustrate that device 10 is configured for convenienttreatment of aneurysm 14, and in particular, a generally symmetricallyshaped aneurysm. However, asymmetrically shaped aneurysm sacs, or thosehaving an otherwise irregular geometrical shape present other problems.For example, if aneurysm sac 16 had a cavity extending out one sidethereof, it may be difficult for liner 24 to fill that portion of theaneurysm sac.

FIGS. 2A and 2B illustrate yet another embodiment of an aneurysmtreatment device 40 in accordance with another embodiment of the presentinvention. Aneurysm treatment device 40 is similar, in many ways, to theprevious embodiments, in that it can illustratively include interiorextender coils 21 and 22 (and optional coils therebetween) and can bepositioned over a guidewire 26 using a detachable delivery catheter 20.Treatment device 40 also illustratively includes a liner 24.

However, treatment device 40 also includes other or different features.FIG. 2A shows treatment device 40 having already been positioned withinan asymmetrical aneurysm sac 16, which has a highly irregular geometry.FIG. 2A shows that treatment device 40 not only includes liner (firstportion) 24, but also illustratively includes a reinforcing layer (orsecond portion) 42. Liner 24 and layer 42 are described in greaterdetail below.

FIG. 2B shows partial deployment of aneurysm liner 24 after guidewire 26has been removed and extender coils 21 and 22 fall away from axialalignment with one another. Liner 24 is also at least partially expandedto the position shown in FIG. 2B through the introduction of embolicmaterial therein to slightly elevate the internal pressure in liner 24above ambient (e.g., 0-1 ATM), using catheter 20.

In accordance with one embodiment of the present invention, liner 24 isillustratively formed of a polymer that has a very low yield strengthand a low elasticity so that, with a minimal amount of additional forceexerted by the embolic material (e.g., 0-5 ATM and illustratively 0-2ATM or 1-2 ATM), the polymer material forming liner 24 readilyplastically expands to conform to the interior perimeter of aneurysmalsac 16. This is illustrated in FIG. 2C. In other words, liner 24 isformed of a polymer having characteristics such that by the continuedintroduction of embolic material into liner 24, liner 24 simplypermanently deforms to assume the shape of the aneurysm sac 16. Thematerial which forms liner 24 also has sufficient ultimate failurestrength so as not to tear during delivery or expansion thereof

In addition, reinforcement layer 42 is more elastic and of a much higheryield strength. Reinforcement layer 42 is illustratively located in theregion of aneurysm liner 24 close to its attachment point to catheter 20(neck portion). This ensures that it will be located preferentially nearaneurysm neck 18 in order to prevent aneurysm liner 24 from expandingthrough neck 18, and into parent vessel 12. Thus, the distal end oftreatment device 40 can easily expand into the irregular geometricalportions of the aneurysmal sac, while the proximal portion thereof doesnot deform as easily and thus prevents deformation into parent vessel12. Reinforcement layer 42 can also be discontinuous or formed of abraid or mesh or polymer material or other reinforcing material and canbe radiopaque as well.

FIG. 2D shows another embodiment of treatment device 40 withperforations formed therein. These perforations allow blood to escapefrom the aneurysmal sac, through liner 24, and reinforcing layer 42,into the parent vessel 12, as liner 24 is expanded. However, as with theprevious embodiments, the perforations are not necessary and the bloodcan simply escape around the outside of device 40 and through neck 18.Also, the perforations are shown as being larger distally, to allowdistal permeation of embolics, although this is optional as well.

For example, spherical PVA embolics may traditionally be 500 microns insize and may be used to fill a conventional aneurysm liner. The distalportion of device 40 can thus be perforated with 750 micron holeswhereas the proximal portion near the neck 18 of aneurysm sac 16 canillustratively be perforated with 350 micron sized, irregularlydistributed, holes. Therefore, as the embolics are introduced into linerportion 24, they are sized to be able to escape the distal end thereofand or occupy the irregular spaces in the aneurysm sac 16, withoutescaping back into the parent vessel 12.

FIGS. 3A-3C illustrate another embodiment of an aneurysm treatmentdevice 50 in accordance with one aspect of the present invention.Similar items are similarly numbered to those shown in previous Figures.Treatment device 50 is similar, in many ways, to the previousembodiments in that it can illustratively include interior extendercoils 21 and 22 (and optional coils therebetween) and can be positionedover a guidewire 26 using a detachable delivery catheter 20. Treatmentdevice 50 also illustratively includes a liner 51.

However, treatment device 50 also illustratively includes other ordifferent features. FIG. 3A shows treatment device 50 having alreadybeen positioned within an asymmetrical aneurysm sac 52, which has ahighly irregular geometry.

In the embodiment shown in FIG. 3A, liner 51 is illustratively formed asa detachable balloon. The balloon material illustratively has aplurality of areas 54 disposed on its surface which are weaker (or moreelastic) than the remainder of the surface of liner 51. In oneillustrative embodiment, areas 54 are simply formed of thinner balloonmaterial than the remainder of liner 51. Of course, they could be formedof different, more elastic (or weaker) material, or the remainder ofliner 51 (other than areas 54) can be enclosed in a braid, a mesh, apolymer material or otherwise coated with a material which precludesthat portion of liner 51 from expanding beyond a predetermined geometryand may be radiopaque as well.

FIG. 3B illustrates aneurysm treatment device 50 expanded under a firstpredetermined pressure. In one illustrative embodiment, liner 51 isinflated with a contrast medium, or saline solution, or another fluidintroduced through catheter 20. As the pressure in liner 51 increases,liner 51 inflates to a first predetermined dimension in which areas 54are not expanded beyond the remainder of liner 51.

FIG. 3C illustrates liner 51, after it has been subjected to additionalinternal pressure. It can be seen that liner 51 has now assumed anirregular shape because the weaker regions 54 have expanded to fill voidspaces of aneurysm sac 52. This allows liner 51 to substantially filleven irregularly shaped aneurysm sac 52. FIG. 3C also illustrates that,in a region of liner 51 proximate neck 18 of the aneurysm there are noweak zones 54. This helps to preclude any portion of the aneurysm liner51 from expanding into parent vessel 12, and thereby fully or partiallyoccluding the vessel.

It should also be noted that, in one illustrative embodiment, liner 51need not even substantially fill the entire aneurysm sac 52. Instead,liner 51 can simply be inflated to a geometry in which enough of theweaker regions 54 have been expanded into void spaces or lobes ofaneurysm sac 52 to securely anchor liner 51 within aneurysm sac 52 andto block the inflow zone through neck 18. In that embodiment, even ifthe entire aneurysm sac 52 is not filled, the neck 18 is blocked anddevice 50 is anchored in place to inhibit further growth of theaneurysm.

In another illustrative embodiment, aneurysm liner 51 can be filled withembolics or other polymeric materials, or coils. This may enhance thelong term stability of liner 51 within aneurysm sac 52.

FIG. 3D is another illustrative embodiment of the present invention.FIG. 3D is similar to the embodiment illustrated in FIGS. 3A-3C, exceptthat it has perforations therein. Weak regions 54 are illustrated bydashed lines while the perforations are illustrated by either points orcircular or oval shaped regions. The perforations allow introducedembolic material to seek out the void spaces, or irregular lobes, ofaneurysm sac 52. The perforations also allow blood that is beingdisplaced in aneurysm sac 52 to re-enter parent vessel 12 throughaneurysm liner 51. Further, the embodiment in FIG. 3D shows that theperforations can be formed to preferentially permeate embolics distally.In other words, the distal perforations are larger than the proximalperforations such that embolics can permeate the distal perforations butnot the proximal perforations. However, the presence of the perforationsare optional, as is the sizing of any perforations which may be used.

Further, weak regions can be other shapes as well, such as annular ringsaround liner 51, axial stripes or substantially any geometric shape.

It should further be noted that all of the embodiments discussed hereincan optionally have biodegradable, cell growth enhancing material suchas polyglycolic acid (PGA) or polylactic acid (PLA) disposed thereon ina region that will illustratively be deployed in a neck region of theaneurysm. Of course, other material or combinations of these materialsmay be used as well.

Also, the devices described herein can be releasably attached toguidewire 26 instead of the catheter.

It can thus be seen that the present invention provides a number ofdifferent embodiments for treating aneurysms. These embodiments addressmany of the various deficiencies and disadvantages associated with prioraneurysm treatment devices.

Although the present invention has been described with reference toillustrative embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

1. A aneurysm occlusion device, comprising: an expandable liner fordelivery within an aneurysm; and a first extender coil disposed withinsaid expandable liner, said first extender coil having a restrainedshape in axial alignment with a delivery device when restrained by saiddelivery device, and a curved relaxed shape when removed from thedelivery device such that said first extender coil bears against theexpandable liner causing the expandable liner to expand toward the wallsof an aneurysm.
 2. The aneurysm occlusion device of claim 1, furthercomprising a second extender coil disposed with said expandable liner,said second extender coil having a restrained shape in axial alignmentwith an delivery device when restrained by the delivery device, and acurved relaxed shape when removed from the delivery device such thatsaid second extender coil bears against the expandable liner causing theexpandable liner to expand toward the walls of an aneurysm
 3. Theaneurysm occlusion device of claim 2, wherein said first extender coiland said second extender coil are biased to extend in oppositedirections when removed from the delivery device.
 4. The aneurysmocclusion device of claim 2, further comprising a reinforcing layerdisposed around a proximal portion of said expandable liner tostrengthen the proximal portion of the expandable liner to prevent theexpandable liner from expanding through a neck of an aneurysm and into aparent vessel of the aneurysm upon inflation of the expandable linerwithin the aneurysm.
 5. The aneurysm occlusion device of claim 1,wherein the expandable liner is perforated to allow blood to escape fromthe expandable liner.
 6. The aneurysm occlusion device of claim 1,wherein the expandable liner is configured to be detachably connected toa delivery catheter.
 7. An aneurysm occlusion device, comprising: anelongated delivery catheter having a proximal end, a distal end and alumen therethrough; an expandable liner for delivery within an aneurysm,said expandable liner detachably connected to the distal end of saidelongated catheter; a guidewire extending through said lumen of saiddelivery catheter and into said expandable liner; a first extender coildisposed within said expandable liner and over said guidewire, saidfirst extender coil having a restrained shape in axial alignment withsaid guidewire when restrained by said guidewire, and a curved relaxedshape when said guidewire is withdrawn from said first extender coilsuch that said first extender coil bears against the expandable linercausing the expandable liner to expand toward the walls of an aneurysm.8. The aneurysm occlusion device of claim 7, further comprising a secondextender coil disposed with said expandable liner and over saidguidewire, said second extender coil having a restrained shape in axialalignment with said guidewire when restrained by said guidewire, and acurved relaxed shape when said guidewire is withdrawn from said secondextender coil such that said second extender coil bears against theexpandable liner causing the expandable liner to expand toward the wallsof an aneurysm
 9. The aneurysm occlusion device of claim 8, wherein saidfirst extender coil and said second extender coil are biased to extendin opposite directions when removed from the delivery device.
 10. Theaneurysm occlusion device of claim 8, further comprising a reinforcinglayer disposed around a proximal portion of said expandable liner tostrengthen the proximal portion of the expandable liner to prevent theexpandable liner from expanding through a neck of an aneurysm and into aparent vessel of the aneurysm upon inflation of the expandable linerwithin the aneurysm.
 11. The aneurysm occlusion device of claim 7,wherein the expandable liner is perforated to allow blood to escape fromthe expandable liner.
 12. The aneurysm occlusion device of claim 7,wherein the expandable liner is configured to be detachably connected toa delivery